Accelerators are widely used to produce radionuclides for a variety of uses including positron emission tomography (PET). Generally, an accelerator produces radionuclides by accelerating a particle beam and bombarding a target material with the accelerated beam thereby producing radionuclides. The type of radionuclides produced are determined by the target material and the particle beam. Typically, a selected target material produces an abundance of one particular radionuclide under selected conditions such that a variety of targets are needed to produce different radionuclides in considerable amounts.
Target changers have been incorporated into accelerators for providing access to multiple targets and for changing targets without having to break down the accelerator system to do so. A target changer must be configured to provide particular services to each target. Specifically, each target and target window must be cooled and the target must be monitored. Most commercial accelerator targets or multiple target systems have separate paths to each target for cooling water, helium window cooling, and target current monitoring. In addition, the connection to the main vacuum enclosure of the accelerator is made when the target is installed, usually by means of a gate valve. This requires six connections to be made or broken if a target is to be removed or added. The connection to the vacuum is particularly critical, and failure to perform this step correctly can result in the loss of vacuum, the recovery of which is very time consuming. Further, the time required for installation and removal of a target is an important consideration because installation or removal is usually done in a high radiation field.
Therefore, it is an object of the present invention to provide a target changer for an accelerator which minimizes the number of connections necessary for installing the targets.
It is another object of the present invention to provide a target changer for an accelerator which is configured to minimize the time necessary to install or remove a target.
Further, it is an object of the present invention to provide a target changer for an accelerator in which there is no impact on vacuum integrity when changing targets
It is yet another object of the present invention to provide a target changer wherein its alignment with respect to the accelerator can not be misadjusted in the field.
It is another object of the present invention to provide a target changer which is designed such that upon removal of the target changer adjustment is not lost.
Moreover, it is an object of the present invention to provide a target changer with which the alignment procedure can be done remotely and dynamically.